Electrical thermostat



April 1930- J. F. MALSBARY 1,752,532

ELECTRICAL THERMOSTAT Filed Jan. 29, 1929 0 INVENTOR.

23 2*; may/Q W W I A TTORNE YS.

Patented Apr. 1, 195%??- UNITED s'rATEs J'OB FOBDYGE MALSBARY, OF FRESNO, CALIFORNIA ELECTRICAL THEBMOSTAT Application filed January 29, 1929. Serial No. 335,895.

My invention relates to an electrical thermostat in which the contact points have a combined sliding and lifting motion when the contact is being broken. It is well known '5 that contact points for making and breaking an electrical circuit frequently fuse so that the automatic action of the thermostat is interfered with. The object of my invention is to produce an electrical thermostat in which the contact points will slide one over the other before the lift is applied to break the contact, thus overcoming the diificulty eX- perienced by the fusing of the points as stated above and insuring positive action of the device.

This and other objects are accomplished by means of the device hereinafter described and illustrated in the accompanying drawing, in which Figure 1 shows a side view of my electrical thermostat partly in section,

showing the contact points closed. Figure 2 i is a similar view of t e device shown in Fig- -ure 1 when the contact points are separated or broken.

Fig. 3 is a top view of the device as shown in Fi 3. land 2.

Re erring to the drawing, 6 is a base preferably constructed of non-conductin material. On base 6 is attached clamp 7 or attaching an electrical conducting wire 8 thereto. Integral with pole 7 is a fixed contact point 9. At one end of base 6 is upright support 10 to which is attached a member 11 constructed of material which will readily expand when heat is applied, and contract as the heat diminishes. In the drawing I have shown member 11 extending outwardly from the upright support 10. It can consist of a tube as shown in Fig. 1 in section, or bars of metal. A sto 12 is attached to the upright support 10. n the drawing I have shown this stop adjustable by means of a screw 13 which can draw the stop toward or from upright support 10.

A contact point 14. is attached to an arm 15, which arm is pivoted at the end opposite the contact point 14 to a bar 16 of non-expansive metal, said bar being attached at one end to the outside end of member 11, and being adapted to slide through the upright wall 10. It will be noted that when the expansive member 11 is shortened or lengthened by the temperature, the non-expansive bar 16 will be moved accordingly in a direction parallel with the member 11. The arm 15 being pivoted to bar 16 will cause the contact point 14 to have a sliding movement. Lever 15 is of such length and positioned so that contact point 14-. is adjacent to the point 9. Lever 15 has a catch 25 positioned thereon so that it engages with stop 12 when the lever is moved to a predetermined position, and said stop then acts as a fulcrum to raise point 14 when the lever 15 is pulled lengthwise. To accomplish this feature the arm 15 has an upward promotion 26, and the pivotal connection 27 is in said upward projection.

In said drawing, contact point 14; is connected by a conducting wire 24 to a block 23 attached to the base, which block is grounded by wire 22. It is noted that block 23 can be eliminated without departing from my invention.

This thermostat has been especially devised for hot water and steam boilers heated by electrical energy, into which boiler the member 11 and bar 16 are inserted. \Vhen the heat in the boiler is sufficient to expand member 11 to a predetermined degree, the nonexpansive bar 16 will pull the point 14 with the sliding motion described until catch 25 engages stop 12, and then bar 16 will pull lever 25 against stop 12, now acting as a fulcrum, and raise the end of the arm having contact point 14 thereon, thus separating the contact the pre etermined degree, member 11 contracts and bar 16 moves arm 15 so that contact point 1 1 again engages contact point- 9, arm 15 moves downward by means of gravity, and the weight of contact point 1% and lever 15.

It is noted that the contact point 1 1 should be insulated from the non-expansive bar 16.

This can be done by the arm 15 being con-- structed of non-conducting material, or by any other well known means of insulating one member from another.

Attention is also called to the fact that a plurality of pairs of contact points can'be oints. Then the boiler cools below automatically broken at different times by pivoting them tothe same non-expansive bar, and by positioning the stop 12 for each separate arm to function at different degrees of 5 heat. This is advisable when it is desirable to cut off portions only of the electrical energy.

Having described my invention, I claim: 1. In an electrical thermostat the combination of a member susceptible of expansion and contraction by a plying heat and cold thereto, a bar having ess expanding characteristics than said member, said member beinlg1 attached at one end to said bar and at the ot er end to a base, adapting said bar to have a movement parallel with said member as the member expands or contracts, an arm having a contact point at one end, an angular extension at the opposite end, and a catch thereon go on the side opposite to the angular extension, said arm being ivotally connected with the non-expanding er and adapted to be moved therewith, stop means adapted to engage the catch in its path of travel, and a fixed contact point positioned to engage the contact olnt on said arm when the arm is in a pre etermined position,

2. In an electrical thermostat the-combination of a base member having a fixed con-- tact point thereon, a cooperating contact point attached to an arm, said arm being pivoted to a non-expansive bar adapting said arm to be moved on said pivot to make or break the contact between said contact points, a member susceptible of greater ex ansion by means of heat than said bar attac ed at one end to said base, said non-expansive bar being attached to the expansive member at the opposite end to the base, a stop member positioned on'the base and a catc on said arm positioned a spaced distance from the pivotal connection on the arm adapted to stop the lateral movement of the arm, said stop member being adapted as a fulcrum when the 5 catch on the arm is en aged therewit 5. F. MALSBARY. 

